Information content for biological classifications

Abstract

Classification is a fundamental activity of the human species. The aim of all forms of classification is to establish a hierarchical structure of information that serves as a reference system to answer specific questions. In biological classification the objective is to store data in a conveniently retrievable fashion, to infer evolutionary relationships, and to predict undocumented characteristics of the included organisms. Different kinds of data have been used to form a basic data matrix from which to construct biological classifications. Dendrograms have been traditionally used to illustrate relationships among taxa, although such two-dimensional diagrams do not capture all relationships from the original data matrix. Controversies have existed on which algorithms are best suited to construct dendrograms. Explicit phyletic (evolutionary), phenetic, and cladistic schools of quantitative classification have each offered methods for doing do, and each has made claims for capturing maximum information. Decisions on which type of data and algorithms to use depend upon the nature of the systematic and evolutionary questions being posed. Important is the need for detailed evolutionary investigations so that inferred relationships can be properly evaluated. Information theory, a separate discipline, is viewed as having high potential to enrich information content of biological classifications.